1. Field of the Invention
This invention relates to an industrial robot control system for controlling the positioning of a robot to a number of programmed operating positions and the execution of programmed operations in association with these operating positions.
2. Description of the Prior Art
In certain robot applications, the robot has to perform a certain work operation at each one of a number of points or locations. This is typically the case, for example, with robots which are used for spot welding. In such a case the robot hand supports a spot welding gun, and the welding process is controlled by a so-called welding control unit connected to the welding gun. The welding control unit is provided with a number of inputs, and, by applying suitable signals at these inputs, the desired welding parameters, for example current intensity and welding time, can be set. During programming of a robot of this kind, the robot is moved to and positioned at each one of the desired welding locations. Then, in the program memory of the robot, there are stored a series of positioning instructions which, during execution of the program, control movement of the robot from welding location to welding location. In addition, in the instruction for each location in the program memory, there must also be stored information stating that a weld is to be carried out and determining the desired welding parameters. A work cycle of the robot often comprises a large number of welding points or locations, and usually the same welding parameters are valid for a sequence of these points. The instruction parts, which define the welding parameters, must then be programmed into each of the welding points, for example by means of pushbuttons on a control unit. For this purpose a relatively large number of depressions of buttons or the like at each welding point is required and the programming work therefore becomes time-wasting.
The above-mentioned problem is, of course, not limited only to spot welding robots but arises generally during the programming of robots, where similar sequences or sets of control signals must be programmed a plurality of times for each work cycle of the robot.
It is of great economical and practical importance that the flexibility of the robot can be utilized to the greatest possible extent by allowing the programming and reprogramming of the robot to be carried out in as simple and fast a manner as possible.